I just had a "new used" center diff installed in my 99 legacy gt wagon 5spd by a reputable independent subaru shop due to a bad viscous coupler.

Shifting, driving, and steering are all very much improved, but I hear a pretty loud whine coming from what seems like the transmission area of the car. It was not there before my car went in for service.The noise seems to become audible at revs over 2.5k. I can also hear a similar noise when coasting to a stop, even with the car in neutral.

I am hoping its some sort of "break in" thing. I am worried they botched the install somehow, or maybe there are bad bearings somewhere that they missed?

What do you think?

octain11

11-22-2012 02:39 PM

could be. do you know what type of diff fluid they used?

EJ25subie05

11-22-2012 03:07 PM

when my center differential failed my bearings went as well. i hope they cleaned that transmission up very well. fluid makes a major difference on noise. i added lucas into my transmission and a lot of the whine went away.

is it a loud whine or just something that you actually have to listen to? when my center differential and bearings went it was loud, i could hear it over my full exhaust. then when i fixed it the whine was there but was very quiet.

bizmackus

11-22-2012 08:11 PM

They used 80w90 gear oil. I checked the dip stick and the level is good, fluid is a light amber & looks clean. Other parts were a gasket and a washer. No mention of bearings so I'm assuming they didn't replace them.

Its a pretty loud whine that is most noticeable at freeway speeds and gets really loud around 80 mph. It definitely increases and decreases with speed. In other words the noise matches the tach.

It almost sounds like a jet engine... kinda funny I guess....:mad:

lleiro

11-28-2012 10:37 PM

I experienced that exact same thing when my 99 Forester REAR diff seized.

There is a chance that you had really bad luck and they both seized at the same time or that there was or there is something causing them to malfunction.

I would have the rear one looked at if I were you...

My center diff on my 2000 gt is being dying for the last year with a lot of torque binding but I never heard the "jet-like" whining sound. I only heard it once running with the donut and once I put back the full size was gone...

octain11

11-29-2012 05:24 AM

op, can be the diffs grinding, i would go back to the shop that had it repaired and let them know. they might have accidentally done something wrong

bizmackus

11-30-2012 05:15 PM

Picked up the car this morning. They replaced 3 bearings in the transmission and now the noise is gone.
Makes me wonder about that shop.. why wouldn't they have replaced the bearings in the first place? Maybe since I have a warranty on the transmission they wanted to do as little work as possible. Turned out to bite them in the ass since they had to do the work twice!!!:lol::lol::lol: